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Alaskan Bearhawk
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Date: 12-9-2008
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Number of Hours: 5.00
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Manual Reference:
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Brief Description: Bending Longerons at Stations N and M
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After yesterdays slight delay, I went ahead and put hot bends on the longerons at stations N and M. First, I took a couple of hours to verify ALL the measurements from front to back and made some minor adjustments. At 2pm, my hired help arrived! A good friend named Dick Woodin volunteered to help make the bends and came over. Dick is no stranger to rag and tube construction, having completely rebuilt a gorgeous "Super Pacer" on floats, along with decades of classic airplane construction experience...and he works cheap.
The first bend was pretty easy, because gravity had its way with the tubing while Dick helped guide it down to the proper position without any preload from the weight of the overhanging tubing. After it had cooled, I set up for the bend from station M to the tail. That is pretty important because it determines the lines of the aft of the fuselage. Again, with me on the torch and Dick lifting the apex where the upper fuselage longerons meet to connect with the tail post, we got it into position. Dick made sure the tubing did have a little preload, because lifting from the aft it puts a little "belly" in the longerons because they are unsupported in the middle. The load has to be neutral when in position because the heat from welding will relieve any residual stresses in the tubing, sometimes with bad results. After the tubing cooled, I put in the supports at station K and removed the clamps at M to see if the tubing would spring up. It was perfect! So, I spent the rest of the evening reinforcing the jig with some triangulation plates to prevent racking and rechecked the alignment. Next to do is to cut and fit the tubes between station L and N and I made the cross tube with the 2 inch peak for station M.
After that, it was late and I didn’t want to do anymore “important” work, so I started to cut steel to make the tubing clamps I’ll need for the tasks ahead. I need them to hold the tubing in position since there isn’t any flat jig table anymore…which is a good thing!
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Slave labor...will work for cookies!
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All measurements are spot on
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All bends done...looking like a fuselage
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